Data alteration checking apparatus and method and recording medium

ABSTRACT

MAC values formed with respect to each file belonging to a directory  122 A and ICVs (D-ICVc) formed on the basis of the MAC values of all files belonging to the directory  122 A are stored into a sequence page  121 A. Sequence pages  121 A,  121 B, . . . formed respectively with respect to all of directories  122 A,  122 B, . . . on a disk and the ICVs formed on the basis of the D-ICVs stored in all of the sequence pages  121 A,  121 B, . . . are stored into a sequence block  114.  Since the MAC values are closed and managed every directory by the sequence pages  121 A,  121 B, . . . , a data alteration check can be executed every directory. An alteration check of data recorded on a recording medium can be efficiently performed.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to data alteration checking apparatus andmethod for checking the presence or absence of alteration with respectto a contents file whose copyright is protected and which has beenrecorded on a recording medium and relates to a recording medium whichis used for such an apparatus.

[0003] 2. Description of the Related Arts

[0004] In recent years, the development of high density optical disksrepresented by a DVD (Digital Versatile Disk) has been progressed andthe standardization of such disks has been progressed in associationwith it. AUDF (Universal Disk Format) has been determined by suchstandardization. A logic format according to the UDF is used in aDVD-RAM (DVD—Random Access Memory) in which a DVD is modified as arewritable disk. The UDF can be also applied to a CD-R in which a CD-ROM(Compact Disc—ReadOnlyMemory) is modified as a writable disk and a CD-RWin which a CD-ROM is modified as a rewritable disk.

[0005] In the UDF, a layer-like file system is used, a sub-directory isreferred to from information stored in a root directory, and furtheranother sub-directory or a substantial file is referred to from theinformation stored in the sub-directory.

[0006] The above construction will be described more specifically. Arecording area on the disk is accessed by using a sector as a minimumunit and, for example, in case of the DVD-RAM, the recording area isaccessed from the inside to the outside of the disk. An area in whichvolume information is written (such an area is referred to as a systemarea here) is arranged subsequent to a lead-in area from the innermostrim side. A position where a file entry (hereinafter, abbreviated to“FE”) of the root directory is written is shown in the system area. TheFE comprises a root directory, a sub-directory, and an allocationdescriptor (hereinafter, abbreviated to “AD”) as information of anaddress and a length of the file.

[0007] In the FE of the root directory, a logic address and a length ofthe root directory as a substance are shown by the AD. The rootdirectory includes one or a plurality of file identifier descriptors(hereinafter, abbreviated to “FIDs”). The FE of the sub-directory or theFE of the file under the root directory is referred to by the FID. Bythose FEs, the substance of the corresponding sub-directory or file isreferred to. The substance of the sub-directory includes one or aplurality of FIDs. That is, in the UDF, the directories other than theroot directory are accessed in the order of the FIDs, FEs, andsubstances by using the FID and FE as pointers.

[0008] There is an alteration check as one of technical elementsregarding the protection of the copyright of the information datarecorded on the recording medium. It is a technique for preventingillegal alteration with respect to the recorded information data anddetecting the alteration in the case where the information data hasillegally been altered. Further, according to the alteration check, bybinding the information data as data closed in the recording medium onwhich the information data has been recorded, an illegal copy of theinformation data can be prevented. In the copyright protection,therefore, such a technique can be regarded as a very importanttechnical element.

[0009] A conventional data alteration checking method will now beschematically explained. An alteration check value which isunconditionally formed and in which it is difficult to identify sourceinformation by a reverse arithmetic operation is obtained every file(contents) as a unit of the information data from attribute informationof the file such as important administration information, copyrightinformation, state information, and the like. The obtained alterationcheck value is written into an alteration check administration valuespace as an area or a file which is provided on the recording medium andwhich cannot be easily accessed by the user. When the recording mediumis reproduced, an alteration check value is obtained on the basis ofreproduction data and the obtained alteration check value is comparedwith the alteration check value written in the alteration checkadministration value space, thereby discriminating whether an illegalmovement or copy of the file has been performed or not.

[0010] Similarly, a method of discriminating whether an illegal movementor copy of the file has been performed or not by obtaining alterationcheck values with respect to all of the files existing on the samerecording medium is also embodied.

[0011] As a method of obtaining the alteration check values, forexample, an arithmetic operating method called MAC (MessageAuthentication Code) specified in ISO/IEC9797 is known. There is a casewhere the alteration check value itself of each file is called MAC. Atthis time, particularly, there is a case where the alteration check withrespect to all of the files existing on the same recording medium iscalled ICV (Integrity Check Value), thereby distinguishing both of them.The alteration check value of each file is called MAC and the alterationcheck values with respect to all of the files on the same recordingmedium are called ICVs hereinbelow.

[0012] According to the conventional alteration checking method, the MACis formed every file on the recording medium as mentioned above. Inrecent years, the realization of a large memory capacity of therecording medium has remarkably been progressed. As the memory capacityof the recording medium increases, the number of files existing on therecording medium also becomes very large and it is presumed that anamount of MAC also becomes very large in association with it. As aprocedure of the above alteration checking method, it is necessary toarithmetically operate the present MACs and ICVs at timing forperforming the check on the basis of the files or the like existing onthe recording medium. At this time, particularly, in case of thedisk-shaped recording medium, a driving system exists in terms of itsstructure and there is a problem such that it takes a long time for theaccess which is performed to obtain information for obtaining the MACsand ICVS. There is also a problem such that it causes a stress to theuser.

[0013] Further, in the case where various kinds of contents exist on thesame recording medium, contents files other than the targets of thealteration check are also included in the alteration checking procedureevery time in dependence on application software or set equipment forreproducing the recording medium. In such a case, it takes surplus timewhich is spent for the alteration check and there is a problem such thata time efficiency is low.

[0014] Further, a case where the alteration checking procedure has to beperformed with respect to a specific file at certain timing is alsoconsidered. In such a case, in the application software or setequipment, the corresponding MAC is searched from an MAC list of therelevant file held at the time of the first alteration check regardingthe recording medium and the alteration check is performed by using thesearched MAC. In this case, if the memory capacity of the recordingmedium becomes large and the number of files existing on the recordingmedium is very large as mentioned above, a scale of the MAC list is alsovery large and it is necessary to spend a long time to specify thecorresponding MAC from the list. There is, consequently, a problem suchthat the time efficiency is low in a manner similar to that mentionedabove.

[0015] As an example of measures for solving the above problem, there isa method whereby an area to store the MAC is set to a fixed length and astoring location of the MAC is directly specified in accordance with thefile number or the like. In case of the recording medium of the largecapacity, however, there is a problem such that it is necessary toassure a fairly large area for this purpose due to a contents storingability.

[0016] According to such a method, since the area to store the MAC isset to the fixed length, there is a problem such that it is necessary tolimit the number of files or the like and it is not practical.

[0017] Hitherto, as a method of binding the information data filesexisting on the recording medium onto the recording medium, a methodwhereby a peculiar ID is embedded into the recording medium and aninformation data file which is recorded onto the recording medium isencrypted by using a contents key to which the ID has been reflected isembodied. A method whereby a certain kind of key is embedded into therecording medium in a state where it is protected by, for example, anencryption or the like and this key is used for encrypting theinformation data is also used likewise. According to both of the abovemethods, for example, even in the case where the file recorded on therecording medium is illegally copied onto another recording medium,since an ID different from that of the recording medium on the copyingsource side has been embedded into such another recording medium, theencryption performed to the information data cannot be decrypted uponreproduction of such another recording medium, so that a state which issubstantially closed in the recording medium can be realized.

[0018] According to such a method, however, when a copy or a movement ofthe file is executed by a legal procedure, it is necessary to decode theinformation data to be copied or moved and encrypt it again by using apeculiar ID or key of the recording medium on the copy or movementdestination side, so that there is a problem such that it is verytroublesome to the user.

[0019] The foregoing alteration check is also used for realizing amechanism similar to that mentioned above. If the ICV can be certainlyheld on the recording medium, even when the file is illegally moved orcopied onto such a recording medium, a mismatch can be detected. At apoint when the mismatch is detected, by obtaining each MAC with respectto all of the files existing on the recording medium at present andcomparing the obtained MACs with the MACs which have already beenrecorded, the files which were illegally moved or copied can bespecified.

[0020] According to the calculation of the ICVs and the checkingprocedure, however, since a procedure to calculate the MACs with respectto all of the files existing on the recording medium is necessary, ittakes a long time for the processes. On the other hand, if only the MACsare used, the files are not always bound on the recording medium.Therefore, in case of the method using the MAC, it is certainlynecessary to use at least the foregoing method using the ICVs or thelike together. At this time, particularly, in case of the disk-shapedrecording medium, the driving system exists in terms of its structureand there is a problem such that it takes a long time for the accesswhich is executed to obtain information for obtaining the MACs and ICVs.There is also a problem such that it causes a stress to the user.

OBJECTS AND SUMMARY OF THE INVENTION

[0021] It is, therefore, an object of the invention to provide dataalteration checking apparatus and method which can efficiently performan alteration check of data and to provide a recording medium which isused for such an apparatus.

[0022] According to the first aspect of the invention, the above objectis accomplished by a data alteration checking apparatus fordiscriminating whether data recorded on a recording medium has beenaltered or not, comprising: reading means for respectively reading out adata block and a file from the recording medium on which with respect toone or each of a plurality of files belonging to a directory serving asan upper concept in which one or a plurality of files are bound, thedata block including one or a plurality of list-type data structureseach including a plurality of first arithmetic operation values whichwere arithmetically operated every file on the basis of attributeinformation of the file by a predetermined arithmetic operating methodwhich is unconditional and does not have a reversible property based ona reverse arithmetic operation has been recorded into an area that isnot accessed by a file system on the recording medium and each of thefirst arithmetic operation values has been written into thecorresponding file; and comparing means for comparing a secondarithmetic operation value which was arithmetically operated by thepredetermined arithmetic operating method on the basis of the attributeinformation of the file read out by the reading means with the firstarithmetic operation value which corresponds to the file and is includedin the list-type data structure corresponding to the directory to whichthe file read out by the reading means belongs in the data block readout by the reading means, wherein on the basis of a result of thecomparison by the comparing means, when the first and second arithmeticoperation values do not coincide, it is determined that the file hasbeen altered.

[0023] According to the second aspect of the invention, there isprovided a data alteration checking method of discriminating whetherdata recorded on a recording medium has been altered or not, comprising:a reading step of respectively reading out a data block and a file fromthe recording medium on which with respect to one or each of a pluralityof files belonging to a directory serving as an upper concept in whichone or a plurality of files are bound, the data block including one or aplurality of list-type data structures each including a plurality offirst arithmetic operation values which were arithmetically operatedevery file on the basis of attribute information of the file by apredetermined arithmetic operating method which is unconditional anddoes not have a reversible property based on a reverse arithmeticoperation has been recorded into an area that is not accessed by a filesystem on the recording medium and each of the first arithmeticoperation values has been written into the corresponding file; and acomparing step of comparing a second arithmetic operation value whichwas arithmetically operated by the predetermined arithmetic operatingmethod on the basis of the attribute information of the file read out bythe reading step with the first arithmetic operation value whichcorresponds to the file and is included in the list-type data structurecorresponding to the directory to which the file read out by the readingstep belongs in the data block read out by the reading step, wherein onthe basis of a result of the comparison by the comparing step, when thefirst and second arithmetic operation values do not coincide, it isdetermined that the file has been altered.

[0024] According to the third aspect of the invention, there is provideda recording medium on which data is recorded by a file structure havinga directory serving as an upper concept in which one or a plurality offiles are bound, wherein with respect to the one or each of theplurality of files belonging to the directory serving as an upperconcept in which the one or the plurality of files are bound, a datablock including one or a plurality of list-type data structures eachincluding a plurality of first arithmetic operation values which werearithmetically operated every file on the basis of attribute informationof the file by a predetermined arithmetic operating method which isunconditional and does not have a reversible property based on a reversearithmetic operation is recorded into an area that is not accessed by afile system and each of the first arithmetic operation values is writteninto the corresponding file.

[0025] As mentioned above, according to the invention, the data blockand the file are respectively read out from the recording medium onwhich with respect to one or each of a plurality of files belonging tothe directory serving as an upper concept in which the one or theplurality of files are bound, the data block including one or aplurality of list-type data structures each including a plurality offirst arithmetic operation values which were arithmetically operatedevery file on the basis of the attribute information of the file by thepredetermined arithmetic operating method which is unconditional anddoes not have the reversible property based on the reverse arithmeticoperation has been recorded into the area that is not accessed by thefile system on the recording medium and each of the first arithmeticoperation values has been written into the corresponding file, thesecond arithmetic operation value which was arithmetically operated bythe predetermined arithmetic operating method on the basis of theattribute information of the read-out file is compared with the firstarithmetic operation value which corresponds to the file and is includedin the list-type data structure corresponding to the directory to whichthe file read out by the reading step belongs in the read-out datablock, and on the basis of the comparison result, when the first andsecond arithmetic operation values do not coincide, it is determinedthat the file has been altered. Therefore, the data alteration check canbe efficiently performed with respect to the time.

[0026] The above and other objects and features of the present inventionwill become apparent from the following detailed description and theappended claims with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]FIG. 1 is a functional block diagram of an example schematicallyshowing an alteration checking method in the case where files have beennewly added onto a disk recording medium;

[0028]FIG. 2 is a functional block diagram showing a procedure in anexample in case of reproducing or moving a certain specific file on thedisk or at timing when an alteration check is requested in a system;

[0029]FIG. 3 is a diagram schematically showing a data structure ofalteration check values according to the embodiment;

[0030]FIG. 4 is a schematic diagram partially showing a physical formatof an example of the disk;

[0031]FIG. 5 is a schematic diagram showing a logic format of an exampleof a sequence block;

[0032]FIG. 6 is a schematic diagram showing a logic format of an exampleof a sequence page;

[0033]FIGS. 7A to 7C are schematic diagrams showing an updatingprocedure of sequence blocks according to an embodiment;

[0034]FIG. 8 is a flowchart showing processes of an example of anupdating procedure of the sequence block including a rescuecountermeasure;

[0035]FIG. 9 is a functional block diagram of an example showing afundamental process for performing a data alteration check according tothe second embodiment;

[0036]FIGS. 10A and 10B are functional block diagrams of an exampleshowing a data alteration checking method according to the secondembodiment;

[0037]FIG. 11 is a schematic diagram showing a data structure of anexample of a PDL;

[0038]FIG. 12 is a functional block diagram of an example showing afundamental process for performing a data alteration check according toa modification of the second embodiment;

[0039]FIGS. 13A and 13B are functional block diagrams of an exampleshowing a data alteration checking method according to a modification ofthe second embodiment;

[0040]FIG. 14 is a schematic diagram showing a logic format of adisk-shaped recording medium which can be applied to the invention incorrespondence to a shape of the disk;

[0041]FIG. 15 is a schematic diagram showing contents of an example of avolume information area;

[0042]FIG. 16 is a schematic diagram for explaining an administratingmethod of directories, files, and empty areas on the disk-shapedrecording medium;

[0043]FIG. 17 is a schematic diagram for explaining an administratingmethod of directories, files, and empty areas on the disk-shapedrecording medium; and

[0044]FIG. 18 is a block diagram showing a construction of an example ofa driving apparatus which can be applied to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] An embodiment of the invention will now be described hereinbelowwith reference to the drawings. First, to make it easy to understand, afundamental data alteration checking method in case of using a disk as arecording medium will be described with reference to FIGS. 1 and 2. Thefundamental alteration checking method which is explained here isobtained by introducing the arithmetic operating method according to theMAC (Message Authentication Code) of ISO/IEC9797. An alteration checkvalue itself which is obtained every file is called an MAC value and thealteration check values which are obtained with respect to all of thefiles existing on the same recording medium are called ICVs (IntegrityCheck Values) hereinbelow.

[0046]FIG. 1 is a functional block diagram of an example schematicallyshowing an alteration checking method in the case where files #1 and #2have newly been added onto a disk recording medium. An MAC value isobtained on the basis of the arithmetic operating method of the MAC withrespect to each of the files recorded in a user data area 110A on a diskrecording medium (hereinafter, abbreviated to a disk) 110. For example,like a file #1 shown in FIG. 1, a predetermined arithmetic operation isexecuted by an MAC arithmetic operating unit 112A by using attributeinformation of the file such as copyright information, importantinformation of the file, and the like and information serving as a keythat is peculiar to this file, for example, a contents key used when anactual data portion of the file is encrypted, so that an MAC value #1 isobtained.

[0047] An MAC value is also similarly obtained with respect to otherfiles. For example, in the file #2, an MAC value #2 is obtained by anMAC arithmetic operating unit 112B from a contents key, attributeinformation of the file such as important information, copyrightprotecting conditions of the file, and the like in a manner similar tothat mentioned above.

[0048] The MAC value can be also obtained by further using the number ofreproducing times of the file, the number of copying times of the file,or the like without limiting to the copyright information, the importantinformation of the file, the contents key, and the like as mentionedabove. For example, by obtaining the MAC value by further using thenumber of copying times of the file, the copy generation of the file canbe restricted.

[0049] The MAC value is a value which is formed by using a hash functionas a unidirectional function on the basis of the given value and theoriginal value cannot be obtained by performing a reverse arithmeticoperation from the MAC value.

[0050] The MAC values #1 and #2 formed with respect to the files #1 and#2 as mentioned above are stored into the corresponding files as headerinformation of the corresponding files, respectively. At the same time,the MAC values #1 and #2 are collectively stored into an area whichcannot be easily accessed by the user in the recording area on the disk110, for example, into a lead-in area 110B prepared on the disk 110. Inthe system in which the disk 110 is handled, the lead-in area 110B is anarea which is not accessed by the file system, that is, an area whichdoes not exist on the logic address in the file system.

[0051] Further, the MAC values #1 and #2 formed every file are inputtedto an MAC arithmetic operating unit 113. A key for an ICV arithmeticoperation is further inputted to the MAC arithmetic operating unit 113.ICVs are formed on the basis of the key for the ICV arithmetic operationand the inputted MAC values #1 and #2. The ICVs are values to whichinformation of all of the files as targets on the disk 110 wasreflected. The formed ICVs are recorded into the lead-in area 110B onthe disk 110 in a manner similar to the foregoing MAC values #1 and #2.

[0052] In the case where the files #1 and #2 were newly added onto thedisk 110 as mentioned above, the MAC values #1 and #2 as alterationcheck values of each file and the ICVs as alteration check values towhich the information of all of the files as targets on the disk 110 wasreflected are recorded in the lead-in area 110B. An area like a lead-inarea 110B in which information regarding the alteration check is storedand a data structure in such an area are called a sequence block here.In FIG. 1, the MAC values #1 and #2 of each file and the ICVs are storedinto a sequence block 114. As mentioned above, the sequence block 114 isrecorded into an area which cannot be easily accessed by the user in therecording area on the disk 110, for example, into the lead-in area 110B.

[0053]FIG. 2 is a functional block diagram showing a procedure in anexample in case of reproducing or moving, for example, a certainspecific file on the disk 110 or at timing when the alteration check isrequested in the system. The alteration check regarding the certainspecific file is executed by using the MAC values. For example, in thecase where the file #1 is reproduced or moved, the MAC value is firstformed with respect to this file by the method which has already beendescribed with reference to FIG. 1. The MAC value which is formed withrespect to the file #1 is assumed to be an MAC value #1′.

[0054] On the other hand, the MAC value #1 which was formed and storedinto a header portion of the file #1 when the file #1 has been recordedonto the disk 110 and the MAC value #1 which was stored into thesequence block 114 in the lead-in area 110B together with the storage ofthe MAC value #1 into the header portion are extracted. Those extractedMAC values #1 are compared with the MAC value #1′ by a comparing unit115A. As a result of this comparison, if the MAC value #1′ does notcoincide with the MAC value #1 extracted from the header portion and theMAC value #1 extracted from the sequence block 114, it is determinedthat there is a fear that an alteration has illegally been performed tothe file #1. An error process is executed in the system.

[0055] The alteration check with respect to all of the files on the disk110 is executed by using the ICVs stored in the sequence block 114. Forexample, in the case where a file (assumed to be the file #1) on thedisk 110 is reproduced or moved, MAC values are first formed with regardto all of the files on the disk 110 in a manner similar to thatmentioned above. With respect to the formed MAC values about all of thefiles, an ICV′ is formed by the MAC arithmetic operating unit 113 byusing the key for the ICV arithmetic operation.

[0056] On the other hand, the ICVs stored in the sequence block 114 inthe lead-in area 110B on the disk 110 are extracted. The ICVs extractedfrom the sequence block 114 are compared with the ICV′ formed from theMAC values of all of the files on the disk 110 by a comparing unit 116.As a result of the comparison, if they do not coincide, it is determinedthat the illegal movement, copy, erasure, or the like of the file hasbeen performed on the disk 110. An error process is executed in thesystem.

[0057] The alteration checking method according to the first embodimentof the invention will now be described in consideration of thefundamental alteration checking method mentioned above. FIG. 3schematically shows a data structure of alteration check valuesaccording to the embodiment. The first embodiment is made by payingattention to the structure of the sequence block 114 in the fundamentalconstructions shown in FIGS. 1 and 2 mentioned above. As a recordingmedium which is applied, the disk 110 as a disk-shaped recording mediumas mentioned above is presumed. In the first embodiment, the recordingmedium which can be applied is not limited to the disk-shaped recordingmedium.

[0058] The sequence block 114 comprises: one or a plurality of sequencepages 121A, 121B, . . . ; and alteration check values ICVs regarding allof the files on the disk 110. Each of the sequence pages 121A, 121B, . .. has a data structure in which the alteration check values of each fileon the disk 110, for example, a plurality of MAC values are stored as alist structure. A process for making each file and the MAC valuescorrespond to each other is performed, for example, by arranging entriesof the MAC values in the sequence page in the order corresponding to thesearching order of a tree structure of the files which is constructed bythe file system.

[0059] As for the files on the disk 110, one or a plurality of files arebound as a directory serving as an upper concept. Each of the sequencepages #1, #2, . . . is made to correspond to the directory in which thefiles corresponding to the MAC values which are stored have been bound.For example, fields for storing IDs such that directories 122A, 122B, .. . and the sequence pages 121A, 121B, . . . correspond to each otherare specified in the sequence pages 121A, 121B, respectively, therebyenabling the correspondence between the directories 122A, 122B, . . .and the sequence pages 121A, 121B, . . . to be obtained.

[0060] For example, the sequence pages 121A, 121B, . . . are allowed tocorrespond to the directories 122A, 122B, . . . formed on the disk 110,respectively. The MAC value formed from each of the files included inthe corresponding directory and ICVs formed by using the MAC values ofall of the files included in this directory as inputs are stored intothe sequence pages 121A, 121B, . . .

[0061] For example, the sequence page 121A corresponding to thedirectory 122A comprises: MAC values #1[0], #1[1], . . . and#1[n−1]formed from files #1[0], #1[1], . . . , and #1[n−1] (not shown)which are stored into the directory 122A; and ICVs formed from the MACvalues of all of the files #1[0], #1[1], . . . , and #1[n−1].

[0062] The ICVs formed by inputting the MAC values of all of the filesincluded in the directory are called D-ICVs hereinbelow. In FIG. 3, “#1′and “#2” are written to distinguish the corresponding directories, andcontents in [ ] are written to distinguish the files which are stored inthe relevant directory.

[0063] Further, the ICVs which are stored into the sequence block 114are formed by inputting all of D-ICV #1, D-ICV #2, . . . which arestored into the sequence pages 121A, 121B, . . . . Therefore, the ICVswhich are stored into the sequence block 114 eventually become thevalues to which the MAC values for the files of the whole disk 110 havebeen reflected.

[0064] As mentioned above, the number of MAC values which are storedinto the sequence pages 121A, 121B, . . . changes in accordance with thenumber of files which are stored into the corresponding directories122A, 122B . . . . Similarly, the number of sequence pages 121A, 121B, .. . which are stored in the sequence block 114 changes in accordancewith the number of directories 122A, 122B, . . . which are formed on thedisk 110. Therefore, the sequence block 114 is constructed as an area ofa variable length and each of the sequence pages 121A, 121B, . . . inthe sequence block 114 is also constructed as an area of a variablelength.

[0065]FIG. 4 partially shows a physical format of an example of the disk110. In the case where the disk 110 is a disk on which data is recordedfrom the inner rim side to the outer rim side of the disk, the upperside of FIG. 4 corresponds to the inner rim side of the disk and thelower side corresponds to the outer rim side of the disk, respectively.The lead-in area 110B is arranged from the inner rim side of the disk. Auser data area is started from the outside of the lead-in area 110B. Theuser data area is an area to which the logic address is allocated andwhich can be accessed by the file system which handles the disk 110. Thelead-in area 110B, on the other hand, is an area which does not exist onthe logic address and which is not accessed by the file system asmentioned above.

[0066] At the head of the lead-in area 110B, an area 130 in which amedia ID is recorded is provided so as to have a size of, for example,132 bytes. An emboss area 131 is arranged after the area of the mediaID. An area in a range from a position next to the emboss area 131 tothe end of the lead-in area 110B is set to a rewritable area 132. Thesequence block 114 is written twice at a predetermined position in therewritable area 132 and the resultant double blocks are assumed to be asequence block 114A and a sequence block 114B, respectively.

[0067] The sequence block 114A is written into a fixed area 133 having asize of, for example, 128 kbytes and starting from the predeterminedposition of the rewritable area 132. The sequence block 114B comprisingthe same data as that of the sequence block 114A is written into a fixedarea 133′ having a size of, for example, 128 kbytes which is arrangedsubsequently to the fixed area 133.

[0068] For example, the sequence block 114A is written in the fixed area133, for example, in the order from the head position. An area 134remaining in the fixed area 133 is filled with stuffing bytes. The fixedarea 133′ is also constructed in a manner similar to the fixed area 133.

[0069]FIG. 5 shows a logic format of an example of the sequence blocks114A and 114B. In the diagram, a numerical value starting from “Ox”denotes that it is expressed by a hexadecimal notation. The sequenceblock 114A will now be described as an example. Bytes are shown in thelateral direction. The total number of entries of the sequence pagesentered in the sequence block 114A is stored in a field “SPE Num” offirst two bytes. A size of the sequence block 114A itself is stored in afield “Block Size” of next four bytes. The number of bytes in a rangefrom the head byte of the sequence block 114A to the last byte of thelast entry is stored.

[0070] A field “Revision” is arranged in 4 bytes subsequent to the field“Block Size”. The number of rewriting times of the sequence block 114Aand a value Revision showing in which state of “valid” or “invalid” thesequence block 114A is are stored in the field “Revision”. An initialstate of the value Revision is set to “0” and the value is increased oneby one each time the sequence block 114A is rewritten. If the sequenceblock 114A is invalid or is being rewritten, the value Revision=InvalidNum and a message indicative of this fact is shown. The value InvalidNum is shown by, for example, a value “OxFFFFFFFF”.

[0071] Six bytes subsequent to “Revision” and next 16 bytes aresystem-reserved. The ICV can be stored into those system reservationbytes. The sequence pages 121A, 121B, . . . are entered from the 133rdbyte. When the information of the sequence pages corresponding to all ofthe directories existing on the disk 110 is entered, the fixed area 133in which the sequence block 114A is stored is filled with, for example,the stuffing bytes of all “0” up to the last byte. Since the sizeinformation of the sequence block 114A itself is described in the field“Block Size”, the stuffing bytes are not always necessary.

[0072] As mentioned above, in the embodiment, the sequence block isconstructed by an assembly of the sequence pages as data structurescorresponding to the directories existing on the disk 110 in aone-to-one relational manner.

[0073]FIG. 6 shows a logic format of an example of the sequence pages121A, 121B, . . . . In the diagram, a numerical value starting from “Ox”denotes that it is expressed by a hexadecimal notation. The sequencepage 121A will now be described as an example. A Page ID for allowingthe sequence page 121A to be concerned with the directory in the filesystem on the disk 110 is stored into a field “Page ID” of first 2bytes. The total number of MAC values which entered the sequence page121A is stored into a field “Entry Num” of next 2 bytes. A size of thesequence page 121A itself is stored into a field “Page Size” of next 4bytes. The number of bytes in a range from the head byte of the sequencepage 121A to the last byte of the last entry is stored. Next 8 bytes aresystem-reserved.

[0074] The D-ICV is stored into a field “D-ICV” of the 17th byte. TheMAC values are stored from the subsequent 33rd byte. The MAC values areset to a fixed length of, for example, 64 bits, that is, 8 bytes. TheMAC values are filled on an 8-byte unit basis from the 17th byte of thesequence page 121A.

[0075] As mentioned above, in the embodiment, a field “Page ID” in whichthe values such as to correspond to the directories on the disk 110 in aone-to-one corresponding manner are stored is specified in the sequencepage. Therefore, in the alteration checking procedure, processes onlywith respect to the specific sequence page as a target in the sequenceblock 114A can be executed. That is, according to the first embodiment,the data alteration check can be performed only with respect to thespecific directory on the disk 110.

[0076] According to the embodiment, the sequence blocks 114A and 114Bfunction mutually as a backup. That is, when a reproduction, a change, acopy, or the like of the file on the disk is executed, the above processis started for one of the sequence blocks and it is updated. Theupdating of the other sequence block is inhibited during the process andit is updated when the process is finished. Thus, for example, even ifthe system-down occurs due to a turn-off of the power source during theprocess or the like, either the sequence block 114A or 114B remainsnormally and the state of the disk 110 can be easily recovered later.

[0077]FIGS. 7A to 7C show an updating procedure of the sequence blocks114A and 114B according to the embodiment. FIGS. 7A and 7B show atransition of the state of the field “Revision” in the sequence blocks114A and 114B, respectively. In FIGS. 7A to 7C, it is assumed that thetime advances from the upper side to the lower side of the diagram. Itis assumed that a file process such as updating or copy of the filewhich is recorded on the disk 110, new recording of the file, or thelike is started at time A and the process is finished at time B. FIG. 7Cshows the value of the field “Revision” at each time. It is assumed thatboth of the values of the field “Revision” of the sequence blocks 114Aand 114B are initially equal to Revision=n−1.

[0078] When the file process for the files on the disk 110 is started attime A, the sequence block 114B is once deleted. At this time, the valueof only the field “Revision” of the sequence block 114B is changed toRevision=Invalid Num and remains, or simultaneously with the start ofthe file process at time A, the existing sequence block 114B isoverwritten by the sequence block 114B comprising only the field“Revision” (and a field “SPE Num” and the field “Block Size”) whosevalue is Revision=Invalid.

[0079] On the other hand, the sequence block 114A is not changed even ifthe file process on the disk 110 is started at time A and the value ofthe field “Revision” is held to Revision=n−1.

[0080] When the file process is finished at time B, a result of the fileprocess is reflected and the sequence block 114B in which the value ofthe field “Revision” is set to Revision=n is written. That is, the valueof the field “Revision” is increased to a value which is larger than thevalue before the file process by “1”. The MAC values and the D-ICVsregarding all of the files and directories on the disk 110 arecalculated again and the sequence page is reconstructed and stored intothe sequence block 114B.

[0081] When the writing of the sequence block 114B is finished, thewriting of the sequence block 114A is started. First, the value of thefield “Revision” of the sequence block 114A is set to Revision=InvalidNum and the sequence block 114A is invalidated (time C). The result ofthe file process is reflected and the sequence block 114A in which thevalue of the field “Revision” is set to Revision=n is written. Afterthat, the sequence blocks 114A and 114B comprise the same data and havethe same Revision=n in the field “Revision”.

[0082] By updating the sequence blocks 114A and 114B as mentioned above,either the sequence block 114A or 114B is certainly valid at any timeshown in FIGS. 7A to 7C. Therefore, even if a system-down occurs due tosome reason during the file process such as recording, copy, or the likeof the data, its rescue countermeasure can be performed.

[0083] That is, when the system is recovered, the MAC values, ICVs, andD-ICVs are formed from the files and directories on the disk 110 in thepresent situation. Those formed values are compared with contents of thesequence value which is valid just after the system recovery in thesequence blocks 114A and 114B. By obtaining a difference between them,some rescue countermeasure can be taken.

[0084]FIG. 8 is a flowchart showing processes of an example of theupdating procedure of the sequence block including the rescuecountermeasure. Processes according to this flowchart are executed inthe case where the data recorded in the sequence blocks 114A and 114B isupdated.

[0085] First, in step S10, the values (referred to as Revision #1 andRevision #2) of the fields “Revision” of the sequence blocks 114A and114B are compared. As a result of the comparison, if Revision #1 andRevision #2 do not coincide, the processing routine advances to stepS11.

[0086] In step S11, the data of the sequence block in which the value ofthe field “Revision” is equal to Revision≠Invalid Num between thesequence blocks 114A and 114B is read out. The data as a target to beread out is the data of each of the sequence pages stored in thissequence block. This data is assumed to be data A.

[0087] In next step S12, the MAC arithmetic operation is executed on thebasis of the data on the disk 110 in the present situation and data ofthe sequence block is newly formed. At this time, in a manner similar tostep S11 mentioned above, the data as a target to be formed is thesequence page based on the file or directory on the disk 110. This datais assumed to be data B.

[0088] In step S13, the data A and data B are compared. As a result ofthe comparison, if it is determined that the data A and data B coincide,it is regarded that there is no problem, a series of processes accordingto the flowchart is finished, and the processing routine advances to theordinary process. If it is decided in step S13 that the data A and dataB do not coincide, the processing routine advances to step S14.

[0089] In step S14, a difference between the data A and data B isextracted and a rescue countermeasure of the files on the disk 110 istaken on the basis of the difference. For example, by obtaining thedifference between the data A and data B, although the file or directoryought to exist according to the sequence block on the disk 110, it doesnot actually exist can be found. Similarly, by comparing the data A anddata B, the file or the like which has the MAC value different from theMAC value recorded in the sequence block because the copyrightinformation or the like of a predetermined file has been rewritten canbe found.

[0090] A rescue countermeasure is taken to such a file if possible. Forexample, the file can be forcedly constructed by adding an EOF (End OfFile) to a predetermined position in the data. With respect to the filehaving a fear that an illegal copy, an illegal rewriting of thecopyright information, or the like has been performed, it is alsopossible to insert attributes indicating that the reproduction isimpossible to such a file or delete the file.

[0091] After the difference between the data A and data B was extractedand the file rescue countermeasure was taken, an updating procedure ofthe sequence blocks 114A and 114B is executed as mentioned above withreference to FIGS. 7A to 7C.

[0092] In step S10, the values Revision #1 and Revision #2 of the fields“Revision” of the sequence blocks 114A and 114B are compared. If it isdetermined that they coincide, the processing routine advances to stepS15. In step S15, with respect to the sequence blocks 114A and 114B,whether the data of the other fields coincide or not is furtherdiscriminated. If it is decided that they coincide, it is regarded thatthere is no problem. A series of processes according to this flowchartis finished and the processing routine advances to the ordinary process.

[0093] In step S15, if it is determined that the data of the otherfields does not coincide, the processing routine advances to step S16and an error correcting process of the sequence block 114A or 114B isexecuted. When the error correcting process of the sequence block isexecuted, a series of processes according to this flowchart is finishedand the processing routine advances to the ordinary process.

[0094] The error correcting process in step S16 can be executed, forexample, as follows. The information of the files or directoriesexisting on the disk 110 is obtained, the MAC value of each file, theD-ICV of each directory, and further, the ICV of the whole disk 110 areformed on the basis of the obtained information. The sequence block inthe present situation on the disk 110 is formed. The formed sequenceblock is compared with the sequence blocks 114A and 114B read out fromthe disk 110, respectively. The sequence block which coincides with thenewly formed sequence block between the sequence blocks 114A and 114B isused as a reference and the updating procedure of the sequence blockmentioned above in FIGS. 7A to 7C is executed.

[0095] A first application example of the data alteration checkingmethod according to the invention will now be described. The firstapplication example is an example which is suitable when it is used inthe case where the files of the same kind are collectively stored everydirectory on the disk 110. More specifically speaking, a plurality ofdirectories A, B, C, . . . which are formed to one disk 110 areconstructed by different kinds of files every directory A, B, C, . . . .For example, the directory A is constructed by a still image file, thedirectory B is constructed by a motion image file, and the directory Cis constructed by an audio file, respectively. As mentioned above, incase of considering a multi-purpose medium as a recording medium, manykinds of data exist on the same recording medium.

[0096] With respect to the alteration check, generally, it is presumedthat it is relatively frequently performed when the recording medium isset into an application, the power source of the apparatus is turned onin a state where the disk 110 is loaded into the disk drive, or thelike. Similarly, in the case where data is newly recorded to therecording medium or a copy or movement of a file to another recordingmedium occurs, the re-calculation of the ICV and the updating of thesequence blocks 114A and 114B are executed on the recording medium.

[0097] The application used here denotes a construction which canperform the recording, reproduction, or the like to the recordingmedium, such as application software installed in a computer apparatus,dedicated apparatus in which hardware and software are integratedlyconstructed, or the like.

[0098] On the other hand, all of the data existing on the recordingmedium cannot be always handled in dependence on the application. Forexample, in case of a music reproduction-only apparatus, if only thedirectory constructed by music files are used as targets, the medium isclosed in this directory, and the alteration checking procedure isenabled to be executed, a time-dependent efficiency can be improved.Particularly, if the recording medium has a disk-shape like a disk 110mentioned above, a time that is required to access to a predeterminedaddress is relatively long in terms of its structure. As a recordingcapacity further increases, such a time-dependent efficiency cannot beignored.

[0099] According to the first embodiment, the sequence page comprises:the MAC value of each file constructing one directory; and the ICVsformed by inputting all of the MAC values of this directory. Thesequence pages corresponding to all of the directories on the recordingmedium are added with the fields in the sequence block and stored.Therefore, the closed alteration check can be performed in each sequencepage. Thus, in case of collectively storing the same kinds of filesevery directory as mentioned above, by applying the alteration checkingmethod according to the invention, the alteration check can beefficiently performed with respect to the time.

[0100] A second application example of the alteration checking methodaccording to the first embodiment will now be described. The secondapplication example is an example which is suitable when it is used inthe case where a directory of the data whose copyright is protected anda directory of the data such as data which has personally beenphotographed or recorded or data which has been distributed in a freecopyright state and whose copyright is not protected are separatelyrecorded.

[0101] In case of the data whose copyright is not protected as mentionedabove, the copy, movement, updating, or the like can be inherentlyperformed without passing through a security system such as analteration check or the like. However, if such data whose copyright isnot protected is used as a target of the alteration check as mentionedabove, the data cannot be reproduced or deleted according tocircumstances, so that the usability is deteriorated.

[0102] On the other hand, there is also a method whereby whether thefile is used as a target of the alteration check or not is specified ona file unit basis. However, even by this method, if the alterationchecking procedure is closed for the whole recording medium, all of thefiles existing on the recording medium have to be scanned eventually andwhether the alteration check should be executed or not has to bediscriminated with respect to each file. A time-dependent loss occurs ina manner similar to the case mentioned in the above first applicationexample.

[0103] According to the invention, as mentioned above, whether the fileis used as a target of the data alteration check or not can bediscriminated on a directory unit basis. Therefore, by storing the datawhich needs the copyright protection and the data which does not needthe copyright protection into the different directories, thetime-dependent loss can be reduced and the data alteration check can beperformed.

[0104] The second embodiment of the invention will now be described.According to the second embodiment, the MAC values are formed by usingthe information which is physically peculiar and unique and which thedisk-shaped recording medium has. Thus, the files can be bound to thisdisk-shaped recording medium and the illegal copy or the like of thefile to another recording medium can be prevented.

[0105]FIG. 9 is a functional block diagram of an example showingfundamental processes for performing the data alteration check accordingto the second embodiment. In a manner similar to the foregoing firstembodiment, a disk 230 has: a user data area 230A in which user data isrecorded; and a lead-in area 230B which does not have a logic address bythe file system. Further, in the second embodiment, an ID peculiar tothe media has been recorded into a predetermined area on the disk 230 bya method whereby the media peculiar ID is peculiar to the disk 230 andits alteration is impossible or very difficult.

[0106] It is desirable to record the media peculiar ID into an area suchas a lead-in area 230B which cannot be easily accessed by the user.Further, it is preferable to record the media peculiar ID by, forexample, a recording method of a destruction system such that arecording film itself of the disk 230 is destroyed by a laser beam of alarge power or the recording surface of the disk 230 is physicallyscratched in a manner such that the alteration by the user is impossibleor difficult. The invention, however, is not limited to such a method.For example, it is also possible to stamp a peculiar ID onto the surfaceor the recording surface of the disk 230 by using a stamper or the likeupon shipping of the disk 230 and use it as a media peculiar ID.

[0107] The MAC value is calculated on the basis of the MAC arithmeticoperating method with respect to each of the files recorded in the userdata area 230A on the disk 230. At this time, the foregoing mediapeculiar ID is also read out and used as an input at the time of the MACarithmetic operation. Referring again to FIG. 9, the attributeinformation of the file such as copyright information and importantinformation of the file and the information serving as a key that ispeculiar to the file, for example, the contents key used at the timewhen the actual data portion of the file is encrypted are read out fromthe file #1 recorded on the disk 230 and supplied to an MAC arithmeticoperating unit 231.

[0108] The MAC arithmetic operating unit 231 forms the MAC value #1 byusing the important information of the file and the contents key whichwere obtained from each file and the media peculiar ID recorded on thedisk 230. The formed MAC value #1 is stored into the file #1 as headerinformation of the file #1 and stored into a sequence block 232. Thesequence block 232 is recorded into the lead-in area 230B. The sequenceblock 232 corresponds to the sequence block 114 and indicates an area inwhich the information regarding the alteration check is stored and itsdata structure.

[0109]FIGS. 10A and 10B are functional block diagrams of an exampleshowing a data alteration checking method according to the secondembodiment. First, as shown in FIG. 10A, by a method similar to thatshown in FIG. 9, the MAC value #1 is formed from the information on thefile #1 and the media peculiar ID and the formed MAC value #1 is storedinto the file #1 as header information to the file #1. The MAC value #1is stored into the sequence block 232 together with the MAC values ofthe other files on the disk 230. A case where the file #1 is copied ormoved into a disk 230′ different from the disk 230 without using a legalprocedure is now considered.

[0110] In a manner similar to that mentioned above, the media peculiarID has been recorded in, for example, the lead-in area 230B on the disk230′. The media peculiar IDs recorded on the disk 230 and 230′ areassumed to be a media peculiar ID-1 and a media peculiar ID-2,respectively. The media peculiar ID is peculiar to the recording media.The media peculiar ID-1 of the disk 230 and the media peculiar ID-2 ofthe disk 230′ are set to different values.

[0111] When the file is copied or moved, as shown in FIG. 10B, the dataalteration check is performed on the disk 230′ on the movementdestination side. First, the important information of the file and thecontents key are extracted from the header information of the file #1 onthe disk 230′ and supplied to the MAC arithmetic operating unit 231. Atthe same time, the media peculiar ID-2 of the disk 230′ is read out andsupplied to the MAC arithmetic operating unit 231. In the MAC arithmeticoperating unit 231, the MAC arithmetic operation is executed by usingthe important information of the file, the contents key, and the mediapeculiar ID-2 which were supplied, thereby forming the MAC value #1′.The formed MAC value #1′ is supplied to a comparing unit 233.

[0112] On the other hand, the MAC value #1 formed on the basis of themedia peculiar ID-1 on the disk 230 on the copying source side has beenstored in the header information of the file #1. The MAC value #1 isread out from the header of the file #1 and supplied to the comparingunit 233.

[0113] In the comparing unit, the supplied MAC value #1 and MAC valueE1′ are compared. The media peculiar ID-1 of the disk 230 and the mediapeculiar ID-2 of the disk 230′ are different as mentioned above.Therefore, even if the file #1 on the disk 230 on the copying sourceside and the file #1 on the disk 230′ on the copy destination side havesubstantially the same contents, the MAC value #1 formed by using themedia peculiar ID-1 and the MAC value #1′ formed by using the mediapeculiar ID-2 are different, so that the dissidence of the MAC values iscaused.

[0114] Further, since the copy of the file #1 onto the disk 230′ hasbeen performed without using the legal procedure, the MAC valuecorresponding to the copied file #1 is not stored in a sequence block232′ on the disk 230′. Therefore, as shown in FIG. 2 mentioned above,when the MAC value stored in the sequence block 232′ is compared withthe MAC values of all of the files on the disk 230′, illegality isdetected.

[0115] According to the second embodiment as mentioned above, althoughthe file can be copied or moved between the different disks, the filewhich was illegally copied or moved can be detected on the copy ormovement destination side. Therefore, the reproduction of the relevantfile from the disk on the copy or movement destination side can beinhibited or the deletion or the like of the relevant file from the diskon the copy or movement destination side can be performed. Thus, acertain file can be substantially bound onto a certain disk.

[0116] According to the second embodiment, it will be understood thatthe ICV is not always necessary for the data alteration check. Althoughthe ICV is used for keeping a matching property of the files existing onthe same recording medium, since the MAC arithmetic operation isexecuted to all of the files existing on the recording medium astargets, the time-dependent efficiency is low. By using the secondembodiment, however, since the recording medium and the filessubstantially correspond to each other in a one-to-one relationalmanner, even if there is no ICV, the matching property in the wholerecording medium can be held.

[0117] Particularly, when the recording medium has a disk-like shape, atime that is required to access to a predetermined address is relativelylong in terms of its structure. As the recording capacity increases, thetime-dependent efficiency can not be ignored. This problem can bereduced by using the second embodiment.

[0118] A modification of the second embodiment will now be described. Inthe foregoing second embodiment, the media peculiar ID as an ID which ispeculiar to the recording medium and whose alteration is impossible ordifficult is used as an input at the time of the MAC arithmeticoperation. On the other hand, according to the modification, defectinformation which was recorded on the recording medium and indicates adefect of the recording medium is used as an input at the time of theMAC arithmetic operation. Since the defect information has a differentvalue every recording medium at an enough large probability, it canbecome the information peculiar to the recording medium. Therefore, thealteration check similar to that in the foregoing second embodiment canbe performed by using the defect information.

[0119] Physical defects of the recording area certainly occur on thedisk-shaped recording medium upon manufacturing. The physical defects ofthe recording area which occurred upon manufacturing are called defects.The defects occur in a random-number manner in the manufacturing step ofthe disk-shaped recording medium. A probability such that anotherdisk-shaped recording medium having substantially the same defect stateas that of a certain disk-shaped recording medium exists in amanufacturing lot is sufficiently small. Therefore, the defectinformation can be regarded as physical information that is peculiar inthe disk-shaped recording medium.

[0120] As a prerequisite of the above modification, upon shipping of thedisk-shaped recording medium, the defect state is verified and defectinformation called PDL (Primary Defect List) to which the defect stateof each minimum recording unit has been reflected is recorded onto eachdisk. FIG. 11 shows a data structure of an example of the PDL. The PDLconsists of a bit train and first 16 bits are set to a fixed valueshowing that the data is the PDL. Each of the subsequent bits indicateseach of the minimum recording units of the disk-shaped recording mediumin accordance with, for example, the address ascending order and is setto the high level. That is, it is shown that the defect exists in theminimum recording unit corresponding to the bit whose value is equal to“1” and this minimum recording unit cannot be used. Such a bit train isrecorded over the whole number of minimum recording units of thedisk-shaped recording medium. Assuming that the whole recording capacityof the disk-shaped recording medium is equal to, for example, 2 GBytes,the PDL has a capacity of 2 to 16 kbytes.

[0121] It is necessary to record the PDL into an area which cannot beeasily accessed by the user such as a lead-in area on the disk-shapedrecording medium lest the PDL itself is altered.

[0122] In the modification of the second embodiment, the PDL is used inthe MAC arithmetic operation. Thus, the files recorded on thedisk-shaped recording medium are the closed files on this disk-shapedrecording medium.

[0123]FIG. 12 is a functional block diagram showing an example offundamental processes for performing the data alteration check accordingto the modification of the second embodiment. In a manner similar to thefirst and second embodiments mentioned above, a disk 240 has: a userdata area 240A in which user data is recorded; and a lead-in area 240Bwhich does not have a logic address by the file system. The PDL isrecorded in the lead-in area 240B.

[0124] An MAC value is calculated on the basis of the MAC arithmeticoperating method with respect to each of the files recorded in the userdata area 240A of the disk 240. At this time, the foregoing PDL is alsoread out and used as an input at the time of the MAC arithmeticoperation. Referring to FIG. 12, important information such as copyrightinformation and the information serving as a key that is peculiar tothis file, for example, a contents key used when an actual data portionof the file is encrypted are read and supplied to an MAC arithmeticoperating unit 241. On the other hand, the PDL recorded in, for example,the lead-in area 240 is read and supplied to the MAC arithmeticoperating unit 241.

[0125] In the MAC arithmetic operating unit 241, the MAC value #1 isformed by using the important information and the contents key whichwere obtained from each file and the PDL recorded on the disk 240. Theformed MAC value #1 is stored into the file #1 as header information ofthe file #1 and stored into a sequence block 242. The sequence block 242is recorded into the lead-in area 240B.

[0126]FIGS. 13A and 13B are functional block diagrams showing an exampleof a data alteration checking method according to the modification ofthe second embodiment. First, as shown in FIG. 13A, by a method similarto that shown in FIG. 12 mentioned above, the MAC value #1 is formedfrom the information on the file #1 and the PDL and the formed the MACvalue #1 is stored into the file #1 as header information of the file#1. The MAC value #1 is also stored into a sequence block 242 togetherwith the MAC values of the other files on the disk 240. A case where thefile #1 has been copied or moved onto a disk 240′ different from thedisk 240 without performing a legal procedure is now considered.

[0127] The PDL has been recorded, for example, into the lead-in area240B on the disk 240′ in a manner similar to that mentioned above. ThePDLs recorded on the disks 240 and 240′ are called PDL-1 and PDL-2,respectively. A probability that these PDL-1 and PDL-2 have the samevalue is extremely small as mentioned above.

[0128] When the file is copied or moved, as shown in FIG. 13B, the dataalteration check is performed on the disk 240′ on the movementdestination side. First, the important information of the file and thecontents key are extracted from the header information of the file #1 onthe disk 240′ and supplied to the MAC arithmetic operating unit 241. Atthe same time, the PDL-2 of the disk 240′ is read out and supplied tothe MAC arithmetic operating unit 241. In the MAC arithmetic operatingunit 241, the MAC arithmetic operation is executed by using theimportant information of the file, the contents key, and the PDL-2,thereby forming an MAC value #1′. The formed MAC value #1′ is suppliedto a comparing unit 243.

[0129] The MAC value #1 formed on the basis of the PDL-1 in the disk 240on the copying source side has been stored in the header information ofthe file #1. The MAC value #1 is read out from the header of the file #1and supplied to the comparing unit 243.

[0130] The comparing unit compares the supplied MAC value #1 and MACvalue #1”. As mentioned above, since a probability that the PDL-1 of thedisk 240 and the PDL-2 of the disk 240′ coincide is extremely small,even if the file #1 on the disk 240 on the copying source side and thefile #1 on the disk 240′ on the copy destination side have substantiallythe same contents, the MAC value #1 formed by using the PDL-1 and theMAC value #1′ formed by using the PDL-2 are different at an extremelyhigh probability, so that the dissidence of the MAC values occurs.

[0131] Further, since the file #1 was copied to the disk 240′ withoutperforming the legal procedure, the MAC value corresponding to thecopied file #1 is not stored in a sequence block 242′ on the disk 240′.Therefore, when the MAC value stored in the sequence block 242′ iscompared with the MAC values of all of the files existing on the disk240′, the illegality is detected.

[0132] As mentioned above, even in the modification of the secondembodiment, in a manner similar to the second embodiment, although thefile can be copied or moved between the different disks, the file whichwas illegally copied or moved can be detected on the copy or movementdestination side. Therefore, for example, the reproduction of therelevant file from the disk on the copy or movement destination side canbe inhibited or the deletion or the like of the relevant file from thedisk on the copy or movement destination side can be performed. Thus, acertain file can be substantially bound onto a certain disk.

[0133] According to the modification of the second embodiment, in amanner similar to the second embodiment, the ICV is not always necessaryfor the data alteration check. Although the ICV is used for keeping amatching property of the files existing on the same recording medium,since the MAC arithmetic operation is executed to all of the filesexisting on the same recording medium as targets, the time-dependentefficiency is low. By using this modification, however, since therecording medium substantially corresponds to the files in a one-to-onerelational manner, even if there is no ICV, the matching property in thewhole recording medium can be held.

[0134] Particularly, when the recording medium has a disk shape, a timethat is required to access to a predetermined address is relatively longin terms of its structure. As the recording capacity further increases,the time-dependent efficiency cannot be ignored. This problem can bereduced by using the modification of the second embodiment.

[0135] The foregoing first and second embodiments and the modificationof the second embodiment can be combined and embodied.

[0136]FIG. 14 shows a logic format of a disk-shaped recording medium 1which can be applied to the invention in correspondence to the shape ofthe disk. The logic format of the disk-shaped recording medium 1conforms with the UDF (Universal Disk Format) mentioned in the priorart. On the disk-shaped recording medium 1 (hereinafter, simply referredto as a disk 1), a lead-in area 10 is arranged at the innermost rimportion. A logical sector number (LSN) is allocated from the outside ofthe lead-in area 10. Subsequently, a volume information area 11, areasDAN-1 (Data Area Number-1), DAN-2, and DAN-3, and a volume informationarea 12 are arranged in order. A lead-out area 13 is arranged in theoutermost rim portion. Logical block numbers are allocated to the areasDAN-1 to DAN-3.

[0137]FIG. 15 shows contents of an example of the volume informationareas 11 and 12. A VRS (Volume Recognition Sequence), an MVDS (MainVolume Descriptor), and an LVIS (Logical Volume Integrity Sequence) arewritten in the volume information area 11 on the basis of the regulationof the UDF. An anchor point is put to the end of the volume informationarea 11. The contents of the volume information area 11 are writtentwice as an RVDS (Reserve Volume Descriptor Sequence) into the volumeinformation area 12 inside of the lead-out area 13. Anchor points areput to the head and end of the volume information area 12. The anchorpoint at the end of the volume information area 12 corresponds to thelast logical sector number.

[0138] A portion in a range from the logical sector number to (the lastlogical sector number—272) is set to an LVS (Logical Volume Space) inwhich a partition area is provided. The areas DAN-1 to DAN-3 arearranged in the LVS. The area DAN-1 provided on the innermost rim sideof the LVS comprises an FSD (File Set Descriptor) and an SBD (SpaceBitmap Descriptor) based on the regulation of the UDF. The SBD expressesempty area information of the whole disk 1 by setting the flag to “1”every sector. An address of the FE of the root directory of the layerstructure of the file system is shown in the area DAN-1.

[0139] The area DAN-2 is an area in which the FE (File Entry) of thedirectory and the FID (File ID) of its substance are arranged. That is,the FE of the directory and the FID of the substance are collectivelyrecorded in the area DAN-2. In the area DAN-2, a predetermined capacityis previously and continuously held at the time of formatting, whichwill be explained hereinlater. Although the details will be explainedhereinlater, an unused area of the area DAN-2 is assured as a file towhich a specific attribute has been added. The file comprising theunused area of the area DAN-2 is referred to as an EIF (EntryInformation File) hereinafter. By handling the unused area as a file ofEIF, it is possible to prevent the unused area from being recognized asan empty area in the SBD.

[0140] Although already mentioned in the prior art, the FE indicates alocation (address) and a size of the substance of the file or directory.Those information is written by the AD (Allocation Descriptor) in theFE. The FID indicates a name of the file or directory and a location(address) and a size of the FE. Those information is written by an ICB(Information Control Block) in the FID.

[0141] The area DAN-3 is an area in which the FE of the file and itssubstance are put. In the area DAN-3, the FE of the file and the filecorresponding to the FE are continuously arranged with respect to theaddresses. When files are added, the FEs of the files to be added arearranged to the existing files continuously with respect to theaddresses. Further, the substances of the files are arrangedcontinuously with respect to the addresses. By arranging the FEs of thefiles and the substances continuously with respect to the addresses asmentioned above, the files can be accessed at a high speed.

[0142] An administrating method of the directories, files, and emptyareas in the disk-shaped recording medium 1 will now be described withreference to FIGS. 16 and 17. FIG. 16 is a diagram showing the areasDAN-1 to DAN-3 extracted from FIG. 14 mentioned above. It is assumedthat the recording direction of the data is set to be counterclockwiseas shown in an example in FIG. 16. FIG. 17 shows a layer structure of anexample of each FE, FID, and substance.

[0143] For example, it is assumed that the FE of the root directory isstarted from LSN=a. The address and size of the substance of the rootdirectory are shown by the AD in the FE of the root directory. Theaddress of the root directory can be continuously arranged together withthe FE of the root directory and, for example, LSN=a+1. The substance ofthe root directory includes one or more FIDs. The name, address, andsize of the FE of the sub-directory of the root directory (hereinafter,such a sub-directory is abbreviated to a sub-directory) are written inthe FID. The FE of the sub-directory is arranged so as to be continuousto the substance of the root directory and, for example, LSN=a+2. Theaddress and size of the substance of the sub-directory are written bythe AD in the FE of the sub-directory. The address of the substance ofthe sub-directory is arranged so as to be continuous to the FE of thesub-directory and, for example, LSN=a+3. One or more FIDs are includedin the substance of the sub-directory and the names, addresses, andsizes of the files and other sub-directories are written.

[0144] By referring to each FE, FID, and substance as mentioned above,as shown in an example in FIG. 17, the substance of the root directory,the sub-directory information of the root directory, and the like arearranged continuously for the FE of the root directory arranged at apredetermined position of the innermost rim portion of the area DAN-2.

[0145] Referring to FIG. 17, the name, address, and size of the FE ofthe EIF are written by the FID in the substance of the root directory.The address and size of the substance of the EIF are written by the ADin the FE of the EIF. Since the EIF is handled as a file as mentionedabove, its address and size are shown by the FE in a manner similar tothe other files.

[0146] The FE of the EIF is arranged, for example, behind the substanceof the EIF as shown in an example in FIG. 16. A start address and/or anend address and the size of the substance of the EIF are fluctuated independence on an amount of each information which is written into thearea DAN-2.

[0147] The FE of the root directory, the substance of the rootdirectory, the FE of the sub-directory of the root directory, thesubstance of the sub-directory of the root directory, the FE of the EIF,and the substance of the EIF are arranged in the area DAN-2 as mentionedabove.

[0148] The FE of the file and the substance of the file are arranged inthe area DAN-3. The substance of the file is an area in which user dataor the like is actually written. As shown in an example in FIG. 17, theFE of the file in which the name, address, and size have been written bythe FID in the substance of the root directory is arranged in the areaDAN-3. The start address of the FE of the file at this time is assumedto be LSN=d. The address and size of the substance of the relevant fileare shown by the AD in the FE of the file. The substance of the file isarranged so as to be continuous to the FE of the relevant file and, forexample, the start address is set to LSN=d+1.

[0149] As mentioned above, the area DAN-2 is previously held at the timeof the formatting process of the disk 1. Subsequently, a formattingmethod of an example of the disk 1 will be schematically explained. Itis assumed that the lead-in area 10 and lead-out area 13 have alreadyexisted before the formatting process, for example, by beingpreliminarily formed at the time of a pressing step in the manufacturingof the disk 1. The formatting process is progressed from the inner rimside toward the outer rim side of the disk 1.

[0150] When the formatting process is started, the foregoing VRS, MVDS,and LVIS are first written from the outside of the lead-in area 10.Subsequently, the LVS is formed. In the LVS, the area DAN-1 is firstformed. The FSD is written and the position of the root directory isdetermined. The SBD is formed. At this time, by setting the area of theEIF mentioned above to the used area in the SBD, the area of the EIF isassured.

[0151] When the SBD is formed and the area DAN-1 is formed, the areaDAN-2 is subsequently formed from the outside of the area DAN-1. Uponformation of the area DAN-2, the FE of the root directory and thesubstance of the root directory are first continuously written intopredetermined addresses on the basis of the FSD written in the areaDAN-1. Subsequently, the FID of the EIF is added to the substance of theformed root directory. In the FID, the address of the FE of the EIF isdesignated.

[0152] At this time, the attributes of the EIF are designated in theFID. The attributes of the EIF which are designated are used forpreventing the EIF from being subjected to the erasure, rewriting,movement, or the like by another apparatus or OS(Operating System). Forexample, a “hidden file attribute”, a “system file attribute”, and a“read-only file attribute” are designated together as attributes of theEIF.

[0153] The “hidden file attribute” is an attribute for disabling thefile to which this attribute has been set to be browsed by an ordinarymethod. The “system file attribute” is an attribute for showing that thefile to which this attribute has been set is a file that is necessaryfor the system. The “read-only file attribute” is an attribute forshowing that the file to which this attribute has been set is aread-only file and its change and erasure are inhibited by the system.By designating all of those three attributes into the file, the processfor erasure, rewriting, movement, or the like to the file cannot beexecuted except for the purpose operation. Those attributes can bedeleted by a predetermined method.

[0154] Subsequently, the FE of the EIF is formed. As mentioned above, inthe FE, the address and size of the relevant file are designated.Therefore, merely by designating the FE, the relevant file exists and itcan be used as a dummy file. The “read-only file attribute” and “systemfile attribute” are designated in the FE of the EIF.

[0155] By allowing the EIF to exist in the area DAN-2 as mentionedabove, the empty area in the area DAN-2 can be held by the EIF. Asmentioned above, after completion of the formatting process, the FE andsubstance of the sub-directory are written into the DAN-2. At this time,the area of the EIF is deleted and the FE and substance of thesub-directory are formed in the area DAN-2.

[0156] Although the details will be explained later, the forming orderof the area DAN-2 is not limited to the foregoing order but this areacan be also formed in another order. At this time, an arranging order ofeach information in the area DAN-2 also changes naturally.

[0157] The area DAN-2 is formed as mentioned above. Although the outsideof the area DAN-2 is the area DAN-3, no process is executed inparticular in the area DAN-3. For example, the following process isexecuted by jumping the area designated as an area DAN-3. The RVDS isformed in the area next to the area DAN-3. As mentioned above, theinformation of the VRS, MVDS, and LVIS which have already been formed iswritten twice. The RVDS is formed and the formatting process of the disk1 is completed.

[0158]FIG. 18 shows a construction of an example of a driving apparatuswhich can be applied to the invention. It is now assumed that aphase-change metal material is used as a recording layer of the disk 1and the driving apparatus records data onto the disk 1 by a phase-changetechnique such that a temperature which is applied to the recordinglayer is controlled by adjusting a power of a laser beam, therebychanging the recording layer to a crystal or amorphous state.

[0159] The disk 1 is rotated by a spindle motor 22. To record data ontothe disk 1 and reproduce the data from the disk 1, an optical pickup 23is provided. The optical pickup 23 is fed in the disk radial directionby a feed motor 24.

[0160] Data from an external host computer 30 is supplied to a drivethrough an interface 29 (for example, SCMS (Serial Copy ManagementSystem)). An encoder/decoder block 25 is connected to the interface 29.A buffer memory 26 is connected to the encoder/decoder block 25. Thebuffer memory 26 holds write data or read data.

[0161] The write data is supplied to the encoder/decoder block 25through the interface 29. The encoder/decoder block 25 forms data of theforegoing format upon recording and subsequently encodes the data inaccordance with this format. Upon reproduction, the encoder/decoderblock 25 performs a decoding process and outputs digital data to thehost computer 30 through the interface 29. In the encoder/decoder block25, for example, the address is added as a subcode and also added to theheader in the data.

[0162] The recording data from the encoder/decoder block 25 is suppliedto a laser driver 28 through a recording equalizer 27. The laser driver28 forms a driving waveform having a predetermined level to record therecording data onto the disk 1. An output of the laser driver 28 issupplied to the optical pickup 23 and the data is recorded. A laserpower of the laser driver 28 is controlled to a proper value by an APC(Automatic Power Control) in an RF signal processing block 31 asmentioned above. A signal generated by the return light from the disk 1is supplied to the RF signal processing block 31. An address extractingcircuit 32 extracts address information on the basis of the signalsupplied from the RF signal processing block 31. The extracted addressinformation is supplied to a microcomputer 33 for control, which will beexplained hereinlater.

[0163] In the RF signal processing block 31, a matrix amplifierarithmetically operates a detection signal of a photodetector, therebyforming a tracking error signal TERR and a focusing error signal FERR.The tracking error signal and the focusing error signal are supplied toa servo block 34.

[0164] The control microcomputer 33 controls the seeking operation byusing the address and executes a control or the like of the laser powerby using a control signal. The control microcomputer 33 comprises a CPU(Central Processing Unit), an RAM (Random Access Memory), an ROM (ReadOnly Memory), and the like and controls the whole driving operation ofthe I/F 29, encoder/decoder block 25, RF signal processing block 31,servo block 34, and the like. A memory 36 is connected to the controlmicrocomputer 33.

[0165] Further, the access to the lead-in area 10 on the disk 1 iscontrolled by the control microcomputer 33. The foregoing sequence blockwhich is recorded into the lead-in area is read out by the controlmicrocomputer 33. The read-out sequence block is stored into, forexample, the memory 36. The header information of the file recorded inthe user area (area DAN-3) on the disk 1 is read out by the controlmicrocomputer 33 and stored into, for example, the memory 36. The mediapeculiar IDs and PDLs which were physically written on the disk 1 asshown in the second embodiment and its modification are also read out bythe control microcomputer 33 and stored into the memory 36.

[0166] The MAC arithmetic operating unit and the comparing unitmentioned above are constructed, for example, in a software manner inthe control microcomputer 33. The MAC arithmetic operating unit and thecomparing unit can be also separately provided in a hardware manner. Bythe MAC arithmetic operating unit, the MAC values or the like asmentioned above are formed on the basis of those information stored inthe memory 36 and the process such as a data alteration check or thelike is executed.

[0167] The RF signal which is obtained by reproducing the disk 1 issupplied to the encoder/decoder block 25. The encoder/decoder block 25executes a decoding process according to a predetermined format such asdemodulation of a modulating process which was performed upon recording,decoding (that is, error correction) of an error correction code, andthe like. In the encoder/decoder block 25, the reproduction data isstored into the buffer memory 26. When a read command from the hostcomputer 30 is received, the read data is transferred to the hostcomputer 30 through the I/F 29.

[0168] A frame sync signal, the tracking error signal, and the focusingerror signal from the RF signal processing block 31 and the addressinformation from the address extracting circuit are supplied to theservo block 34. The servo block 34 executes a tracking servo and afocusing servo for the optical pickup 23, a spindle servo for thespindle motor 22, and a thread servo for the feed motor 24.

[0169] Although the example in which the host computer 30 is connectedto the driving apparatus has been described above, the invention is notlimited to such an example. As an apparatus which is connected to thedriving apparatus, another apparatus can be also connected so long as itinputs and outputs the digital signal and to which the interface isadapted. For example, the driving apparatus can be also built in aportable digital video recorder with a camera in which a photographedimage is recorded onto the disk-shaped recording medium.

[0170] Although the example in which the format data to the disk 1 isformed by the encoder/decoder block 25 has been described above, theinvention is not limited to such an example. The format data can be alsoformed by the control microcomputer 33. The format data can be alsosupplied from the host computer 30.

[0171] As described above, according to the invention, since the MACvalues of the respective files are collectively managed on a directoryunit basis, there is an effect such that the procedure that is requiredfor the data alteration check can be minimized in accordance with thespecification of the application. Particularly, in case of using thedisk-shaped recording medium as a recording medium, there is an effectsuch that the access performance at the time when the data alterationcheck of each file is performed can be remarkably improved.

[0172] According to the invention, since the data for performing thedata alteration check, that is, the data to protect the copyright isbound on a directory unit basis, there is an effect such that the accessperformance for the data which does not need the protection of thecopyright can be assured. There is, consequently, an effect such thatthe data alteration check administration space, that is, the size ofsequence block can be also minimized.

[0173] Further, when the value corresponding to a certain specific fileis searched from the list of the alteration check values (MAC values),since the number of MAC entries in the sequence page corresponding tothe directory as a target becomes a parameter of the search, there is aneffect such that a search efficiency can be improved as compared withthat in case of using the MAC entries of the whole disk as parameters.

[0174] Moreover, since the size of sequence block as an alteration checkadministration space is set to the variable length, the size of sequenceblock can be set to the minimum value according to the number of filesor directories. There is an effect such that the space efficiency andsearch efficiency can be improved.

[0175] As described above, according to the second embodiment of theinvention and the modification of the second embodiment, the informationthat is peculiar to the recording medium, that is, the information whichcannot be easily altered by the user is used together with the attributeinformation of the file or the like and the MAC arithmetic operation isexecuted. Therefore, there is an effect such that even if another newarithmetic operation or mechanism is not introduced, the files recordedon the recording medium can be substantially bound on this disk.

[0176] According to the second embodiment of the invention and themodification of the second embodiment, since the above effects can berealized separately from the encryption of the data recorded in thefile, in the copy or movement of the file according to the legalprocedure, there is no need to modify the data itself and it issufficient to execute the minimum process. There is, consequently, aneffect such that a situation causing a limitation of the usability canbe avoided while preventing the data alteration.

[0177] Further, according to the second embodiment of the invention andthe modification of the second embodiment, since the ICVs used hithertoin case of performing the alteration check with respect to the wholerecording medium are not always necessary, there is an effect such thatthe processing time which is caused at the time of the alterationchecking procedure can be reduced.

[0178] The present invention is not limited to the foregoing embodimentsbut many modifications and variations are possible within the spirit andscope of the appended claims of the invention.

What is claimed is:
 1. A data alteration checking apparatus fordiscriminating whether data recorded on a recording medium has beenaltered or not, comprising: reading means for respectively reading out adata block and a file from said recording medium on which with respectto one or each of a plurality of files belonging to a directory servingas an upper concept in which one or a plurality of files are bound, thedata block including one or a plurality of list-type data structureseach including a plurality of first arithmetic operation values whichwere arithmetically operated every said file on the basis of attributeinformation of the file by a predetermined arithmetic operating methodwhich is unconditional and does not have a reversible property based ona reverse arithmetic operation has been recorded into an area that isnot accessed by a file system on said recording medium and each of saidfirst arithmetic operation values has been written into thecorresponding file; and comparing means for comparing a secondarithmetic operation value which was arithmetically operated by saidpredetermined arithmetic operating method on the basis of the attributeinformation of said file read out by said reading means with said firstarithmetic operation value which corresponds to said file and isincluded in said list-type data structure corresponding to saiddirectory to which said file read out by said reading means belongs insaid data block read out by said reading means, wherein on the basis ofa result of the comparison by said comparing means, when said first andsecond arithmetic operation values do not coincide, it is determinedthat said file has been altered.
 2. An apparatus according to claim 1,wherein a third arithmetic operation value which was arithmeticallyoperated by said predetermined arithmetic operating method by using saidfirst arithmetic operation values of all of said files belonging to saiddirectory with respect to each of said directories included in saidlist-type data structure is further included in said list-type datastructure recorded on said recording medium, and a fourth arithmeticoperation value which was arithmetically operated by said predeterminedarithmetic operating method by using said third arithmetic operationvalues of all of said list-type data structure included in said datablock is included in said data block recorded on said recording medium.3. An apparatus according to claim 2, wherein when said file is read outfrom said recording medium by said reading means, said third arithmeticoperation value of said list-type data structure which corresponds tosaid directory serving as a target and is included in said data blockread out by said reading means is compared with a fifth arithmeticoperation value which was arithmetically operated by said predeterminedarithmetic operating method by using said first arithmetic operationvalues of all of said files belonging to said directory serving as saidtarget, and as a result of said comparison, if said third and fiftharithmetic operation values do not coincide, it is determined that saiddirectory has been altered.
 4. An apparatus according to claim 1,wherein said files are bound in said directory in accordance with a kindof said file.
 5. An apparatus according to claim 4, wherein when thekind of said file indicates the file which does not need the dataalteration check, said data alteration check for said directory to whichthe kind of said file corresponds is not performed.
 6. An apparatusaccording to claim 4, wherein the kind of said file is based on contentsof the data which is stored into said file.
 7. An apparatus according toclaim 4, wherein the kind of said file is based on the presence orabsence of a protection to said file.
 8. An apparatus according to claim1, further comprising recording means for recording the data onto therecording medium, and wherein said data block has a field in which thenumber of updating times of said data block or a value showing that saiddata block is invalid is stored, and said recording means is constructedin a manner such that said data block is written twice into the areawhich is not accessed by said file system, when said data block isrewritten, a value of said field of one of said twice-written datablocks is set to the value showing that said data block is invalid, saidone data block is rewritten, when said rewriting is finished, the valueof said field of said one data block is set to a value indicative of thenumber of updating times of said one data block, a value of said fieldof the other one of said twice-written data blocks is set to the valueshowing that said data block is invalid, said other data block isrewritten, and when said rewriting is finished, the value of said fieldof said other data block is set to a value indicative of the number ofupdating times of said other data block.
 9. An apparatus according toclaim 1, wherein said first arithmetic operation values are arranged inthe searching order of a tree structure in which the corresponding fileis constructed by the file system and are stored into said list-typedata structure.
 10. A data alteration checking method of discriminatingwhether data recorded on a recording medium has been altered or not,comprising: a reading step of respectively reading out a data block anda file from said recording medium on which with respect to one or eachof a plurality of files belonging to a directory serving as an upperconcept in which one or a plurality of files are bound, the data blockincluding one or a plurality of list-type data structures each includinga plurality of first arithmetic operation values which werearithmetically operated every file on the basis of attribute informationof said file by a predetermined arithmetic operating method which isunconditional and does not have a reversible property based on a reversearithmetic operation has been recorded into an area that is not accessedby a file system on said recording medium and each of said firstarithmetic operation values has been written into the correspondingfile; and a comparing step of comparing a second arithmetic operationvalue which was arithmetically operated by said predetermined arithmeticoperating method on the basis of said attribute information of said fileread out by said reading step with said first arithmetic operation valuewhich corresponds to said file and is included in said list-type datastructure corresponding to said directory to which said file read out bysaid reading step belongs in said data block read out by said readingstep, wherein on the basis of a result of the comparison by saidcomparing step, when said first and second arithmetic operation valuesdo not coincide, it is determined that said file has been altered.
 11. Arecording medium on which data is recorded by a file structure having adirectory serving as an upper concept in which one or a plurality offiles are bound, wherein with respect to one or each of said pluralityof files belonging to said directory serving as an upper concept inwhich one or a plurality of said files are bound, a data block includingone or a plurality of list-type data structures each including aplurality of first arithmetic operation values which were arithmeticallyoperated every file on the basis of attribute information of said fileby a predetermined arithmetic operating method which is unconditionaland does not have a reversible property based on a reverse arithmeticoperation is recorded into an area that is not accessed by a file systemand each of said first arithmetic operation values is written into thecorresponding file.
 12. A medium according to claim 11, wherein a secondarithmetic operation value which was arithmetically operated by saidpredetermined arithmetic operating method by using said first arithmeticoperation values of all of said files belonging to said directory withrespect to each of said directories included in said list-type datastructure is further included in said list-type data structure, and athird arithmetic operation value which was arithmetically operated bysaid predetermined arithmetic operating method by using said secondarithmetic operation values of all of said list-type data structureincluded in said data block is included in said data block.
 13. A mediumaccording to claim 11, wherein said files are bound in said directory inaccordance with a kind of said file.
 14. A medium according to claim 13,wherein the kind of said file is based on contents of the data which isstored into said file.
 15. A medium according to claim 13, wherein thekind of said file is based on the presence or absence of a protection tosaid file.
 16. A medium according to claim 11, wherein said data blockis written twice into the area which is not accessed by said file systemand has a field in which the number of updating times of said data blockor a value showing that said data block is invalid is stored, and whensaid data block is rewritten, a value of said field of one of saidtwice-written data blocks is set to the value showing that said datablock is invalid, said one data block is rewritten, when said rewritingis finished, the value of said field of said one data block is set to avalue indicative of the number of updating times of said one data block,a value of said field of the other one of said twice-written data blocksis set to the value showing that said data block is invalid, said otherdata block is rewritten, and when said rewriting is finished, the valueof said field of said other data block is set to a value indicative ofthe number of updating times of said other data block.
 17. A mediumaccording to claim 11, wherein a size of said data block is set to avariable length in accordance with the number of said directoriesexisting on the recording medium on which said data block is recorded.18. A medium according to claim 11, wherein said list-type datastructure is set to a variable length in accordance with the number ofsaid files belonging to said directory to which said list-type datastructure corresponds.
 19. A medium according to claim 11, wherein saidfirst arithmetic operation values are arranged in the searching order ofa tree structure in which the corresponding file is constructed by thefile system and are stored into said list-type data structure.
 20. Adata alteration checking apparatus for discriminating whether datarecorded on a recording medium has been altered or not, comprising:reproducing means for reproducing said recording medium on which uniqueidentification information is fixedly recorded every recording medium,and with respect to one or each of a plurality of files recorded on saidrecording medium, a first arithmetic operation value which wasarithmetically operated on the basis of attribute information of saidfile and said identification information by a predetermined arithmeticoperating method which is unconditional and does not have a reversibleproperty based on a reverse arithmetic operation has been stored; andcomparing means for comparing said first arithmetic operation valuestored in said file reproduced by said reproducing means with a secondarithmetic operation value which was arithmetically operated by saidpredetermined arithmetic operating method on the basis of said attributeinformation of said file reproduced by said reproducing means and saididentification information, wherein on the basis of a result of thecomparison by said comparing means, when said first and secondarithmetic operation values do not coincide, it is determined that saidfile is illegal.
 21. An apparatus according to claim 20, wherein on saidrecording medium, a list-type data structure in which said firstarithmetic operation values of every one or a plurality of said filesrecorded on said recording medium have been stored is recorded into anarea which is not accessed by a file system of said recording medium,and when said file recorded on said recording medium is reproduced bysaid reproducing means, said first arithmetic operation value stored insaid list-type data structure is compared with said second arithmeticoperation value which was arithmetically operated by said predeterminedarithmetic operating method on the basis of said attribute informationof said file reproduced by said reproducing means and saididentification information, and when said first and second arithmeticoperation values do not coincide, it is determined that said file isillegal.
 22. An apparatus according to claim 20, wherein saididentification information is ID information which was uniquelydetermined every said recording medium.
 23. An apparatus according toclaim 20, wherein said identification information is informationindicative of physical defect information of said recording medium. 24.An apparatus according to claim 20, wherein said identificationinformation comprises both of ID information which was uniquelydetermined every said recording medium and physical defect informationof said recording medium.
 25. An apparatus according to claim 20,wherein said attribute information is copyright information of saidfile.
 26. An apparatus according to claim 20, wherein said attributeinformation is present state value information of said file.
 27. A dataalteration checking method of discriminating whether data recorded on arecording medium has been altered or not, comprising: a reproducing stepof reproducing said recording medium on which unique identificationinformation is fixedly recorded every recording medium, and with respectto one or each of a plurality of files recorded on said recordingmedium, a first arithmetic operation value which was arithmeticallyoperated on the basis of attribute information of said file and saididentification information by a predetermined arithmetic operatingmethod which is unconditional and does not have a reversible propertybased on a reverse arithmetic operation has been stored; and a comparingstep of comparing said first arithmetic operation value stored in saidfile reproduced by said reproducing step with a second arithmeticoperation value which was arithmetically operated by said predeterminedarithmetic operating method on the basis of said attribute informationof said file reproduced by said reproducing step and said identificationinformation, wherein on the basis of a result of the comparison by saidcomparing step, when said first and second arithmetic operation valuesdo not coincide, it is determined that said file is illegal.
 28. Arecording medium onto/from which data can be recorded and/or reproduced,wherein unique identification information is fixedly recorded everymedium, and one or a plurality of said files in each of which a firstarithmetic operation value which was arithmetically operated on thebasis of attribute information of said file and said identificationinformation by a predetermined arithmetic operating method which isunconditional and does not have a reversible property based on a reversearithmetic operation has been stored are recorded.
 29. A mediumaccording to claim 28, wherein a list-type data structure in which saidfirst arithmetic operation value of one or each of a plurality of saidrecorded files has been stored is recorded into an area which is notaccessed by a file system.
 30. A medium according to claim 28, whereinsaid identification information is ID information which was uniquelydetermined every said medium.
 31. A medium according to claim 28,wherein said identification information is information indicative ofphysical defect information of said medium.
 32. A medium according toclaim 28, wherein said identification information comprises both of IDinformation which was uniquely determined every said medium and physicaldefect information of said medium.
 33. A medium according to claim 28,wherein said attribute information is copyright information of saidfile.
 34. A medium according to claim 28, wherein said attributeinformation is present state value information of said file.